Flavius Claudius Julianus (331/332[1] – 26 June 363), commonly known as Julian, Julian the Apostate or Julian the Philosopher, was Roman Emperor from 355 to 363 and a noted philosopher and Greek writer.[2]

A member of the Constantinian dynasty, he was made Caesar by Constantius II in 355 and took command of the western provinces. During his reign he campaigned successfully against the Alamanni and Franks. Most notable was his crushing victory over the Alamanni in 357 at the Battle of Argentoratum - despite being outnumbered. In 360 he was acclaimed Augustus by his soldiers, sparking a civil war between Julian and Constantius. However, Constantius died before the two could face each other in battle, naming Julian as his rightful successor. In 363, Julian embarked on an ambitious campaign against the Sassanid Empire. Though initially successful, Julian was mortally wounded in battle and died shortly after.

Julian was a man of unusually complex character: he was "the military commander, the theosophist, the social reformer, and the man of letters".[3] He was the last non-Christian ruler of the Roman Empire and it was his desire to bring the empire back to its ancient Roman values in order to save it from "dissolution".[4] He purged the top-heavy state bureaucracy and attempted to revive traditional Roman religious practices at the cost of Christianity. His rejection of Christianity in favour of Neoplatonicpaganism caused him to be called Julian the Apostate by the church.[5] Interestingly, he was also the last emperor of the Constantinian dynasty - the empire's first Christian dynasty.